You watch their actions...It is as simple as that. You question "What do their actions mean? What are they doing? WHY are they doing it?" Also, you pay attention to what they say...explicitly and implicitly.

Every conscious being is conscious. The only thing is...are they aware of it? or do they deny their consciousness?

To answer the question "How do we know they just don't act like their conscious?" ...You do those following steps...Zombies do not breathe...think...and all they do is moan and eat human flesh...That should be sufficent enough for you to know who is zombie or not

When a man declares: "There are no blacks and whites [in morality]" he is making a psychological confession, and what he means is: "I am unwilling to be wholly good—and please don't regard me as wholly evil!" - Ayn Rand

Only difference is that...I believe you *can* know. Not just believe in the evidence.

When a man declares: "There are no blacks and whites [in morality]" he is making a psychological confession, and what he means is: "I am unwilling to be wholly good—and please don't regard me as wholly evil!" - Ayn Rand

I think we can figure out that other people are conscious by figuring out how consciousness works. Once we figure out what makes the brain conscious and how observable brain activity relates to consciousness, then we can know that people are conscious based on that. In analogy, I know what programs my computer is running by analyzing what is going on overall in the circuits (or by having another computer program analyze all that data for me).

The problem of solipsism is unfortunately meaningless. Even if you can't prove that other consciousness exists, are you going to change anything in your life due to this fact? Try this. If you have a problem with the doubt that other minds exist, I want you to get up tomorrow morning and go to school or work or church or where ever. However, I want you to go completely naked. If it's possible that other minds don't actually exist, then it doesn't matter, right? Though I am quite certain nobody would actually do this. This skeptical possibility is not relevant. The way I see it, I agree, we can't know certain topics like this. But so what? It has no effect on anything else except for the thought experiment itself.

Although not knowing wouldn't change the way I'd act, knowing certainly would. If I could distinguish between conscious creatures and mere zombies many ethical decisions would come a lot easier. Pork? No thanks, pigs are conscious. Chicken? Yes please, they're just zombies.

There is no distinguishing. You are trying to make excuses for things you feel, if only slightly, guilt for doing. What about plants? They grow.
What about fish?
This argument gets you nowhere.
We should just eat people and get it over with.

"I'm not down here for your money, I'm not down here for you love, I'm not down here for your love or money, I'm down here for your soul"

Coffeeprincess,
I'd agree that there's no distinguishing in the strict philosophical sense. Just like there's no way of knowing whether I'm a brain in a vat, or if there's an external reality.
But people distinguish between conscious and non-conscious creatures all the time, if only intuitively, and many make ethical decisions on that basis. All I'm saying is that increased knowledge about consciousness can lead to better ethical decision-making (at least insofar as consciousness is relevant to ethics - it is for utilitarians, not so much for contract-theorists). This is already happening with brain function which, while not consciousness itself, seems to be closely correlated with it.